Preforms having a varying alloy composition and resulting in varying properties needed for the article are state of the art (e.g. German Published Application No. 4 105 420). The production may follow the method of spray deposition (e.g. British Patent Nos. 1 379 261 and 1 472 939) where the molten metal is atomized by a gas jet in a suitable nozzle and the droplets are collected to form a coherent deposit.
According to German Published Application No. 4 105 420, the initial preform is made from an alloy that contains no modifying additions by molten metal being sprayed onto a rotating hollow mandrel. The layers added later on have an alloy composition modified by the modifying additions that are added to the molten metal and sprayed together with it.